JPH0547673B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to improving the controllability of basis weight profile control in a paper machine control system.

<Prior Art> FIG. 5 is a schematic diagram of a papermaking process. Raw material pulp P passes through seed box 1, seed mouth valve 2, and then goes to white water silo 3.
It is combined with the return raw material from the pump 4 and supplied to the head box 5 by the pump 4.

The raw materials in the head box are slice lips 6
The water is discharged in a sheet form from the gap onto the wire in wire part 8, and is squeezed out in press part 9.
After being heated and dried with steam in the drying part 10, it is passed through a calendar 11 and wound onto a reel 12 to become a product.

Reference numeral 7 denotes a plurality of (for example, 40) slice bolts for controlling the gap opening of the slice lip, which act as operating ends.

13 is a B/M meter that scans the product in the paper width direction to measure the basis weight (weight of 1 m ² ) and moisture content of the paper, and based on this measurement value, the absolute dry basis weight profile of the paper can be determined. Multiple points in the width direction, e.g. 60 points or 360 points
Calculated by dividing into points.

The slice lip opening degree is adjusted by operating the slice bolt corresponding to the measurement point using the operation output obtained by controlling and calculating the difference between the calculated dry basis weight profile measurement value at each point and the set value. Feedback control is performed so that the weight profile matches the set bone dry basis weight profile.

Reference numerals 14 and 15 denote a shower supply means, which supplies a shower to a certain section along the wire from both ends of the head box to adjust the direction in which the paper stock is discharged. The supply pressure of the shower is set to an appropriate value by manual operation by the operator, which satisfies the support of the pressure gauge.

<Problems to be Solved by the Invention> In profile control, control of the ear end is very difficult for the following reasons, and manual shower shower operation by an operator is frequently required.

The stock flow velocity at the edge of the slice ripple is slower than that at the center due to the slowing effect of wall resistance.

There is a reflected flow of paper stock from the head box wall, cheeking piece, and Nordeckel shower.

These effects cause the ear tip profile to bounce up or droop down. Moreover, since the only operating end for profile control is a slice rip, it is difficult to perform appropriate corrective control, and the control may actually worsen the profile at the ear end.

Figure 7 shows the measured value PV _p and the set value of the profile.
This shows an example of measurement of SV _p , in which a jump as shown by A occurs in the profile measurement value on the ear end side.

An object of the present invention is to provide a profile control device that can solve these problems.

<Means for Solving the Problems> A structural feature of the present invention is that it is arranged on the lower surface of the rear wire.

<Means for Solving the Problems> The structural feature of the present invention is that the operation output obtained by controlling and calculating the deviation between the basis weight profile measurement signal and the basis weight profile establishment signal corresponding to each measurement point is applied to each measurement point. In the basis weight profile control device, which has a pressure control means for a no-decker shower installed at both ends of the head box, the integrated value of the above-mentioned deviations at a plurality of measurement points near both ends of the slice lip is transmitted to the slice bolt as an operating end for The present invention is characterized in that it includes means for calculating, and means for changing the set value of the pressure regulating means when the calculated output exceeds the dead zone.

<Operation> The integrated value of the profile deviation of a plurality of measurement points near both ends of the slice is calculated, and when the calculated output exceeds the dead zone, the set value of the Nordeckel shower pressure adjustment means is automatically changed and corrected.

<Example> An example of the present invention will be described based on FIG. FIG. 1 is a side configuration diagram of the wire part 8,
Components that are the same as those explained in FIG. 5 are given the same reference numerals, and their explanation will be omitted.

801 is wire, 802 is breast roll,
Reference numerals 803 and 804 indicate suction boxes arranged on the lower surface downstream of the wire, which absorb moisture from the paper stock using negative pressure. 805, 806, and 807 are foils arranged in series on the lower surface upstream of the wire, and scrape off water drops that fall through the wire. A forming board 807 is arranged below the wire of the stock discharge section.

14 is a pipeline for supplying shower water W to the shower supply means 14, 17 is a shower water pressure sensor of the supply pipeline, and PV ₁ is its measured value; 18
is a control valve also inserted into this shower water supply pipe 16.

19 is a pressure regulator, which controls and calculates the deviation between the measured value PV ₁ and the pressure measured value SV ₁ , and outputs the manipulated output MV _1.
is sent to the control valve 18 to set the shower water pressure to the set value.
Adjust to SV ₁ .

Although not shown, a similar pressure regulating means (not shown) also operates in the Nordeckel shower supply means 15 in response to the measured value PV ₂ and set value SV ₂ .

20 is a control device, which controls the measured value of the profile.
PV _p and the set value SV _p are input, a predetermined calculation is performed, and the established pressure values SV ₁ and SV ₂ are supplied to the pressure regulators of the two Nordeck showers and corrected.

FIG. 2 is a block diagram showing a no-decker shear water pressure control loop centered on the control device 20, in which the control device 20 is connected to the deviation integrating means 20.
1, nonlinearization means 202, and shower pressure setting value calculation means 203.

The deviation integration means 201 calculates the deviation △E _i between the measured profile PV _p and the set profile SV _p from the process.
is input, and the integrated deviation E _i corresponding to a predetermined number of slice bolts at both ends of the slice lip is calculated.

In Fig. 3, if the slice bolts are numbered 1, 2...N from left to right, the cumulative deviation E _i1 of the slice bolts 1 to l at the left ear end is E _i1 = _l 〓 ⁱ⁼¹ △E _iSimilarly , the cumulative deviation of the slice bolt k at the end of the right ear
E _i2 becomes E _i2 = _N 〓 ^i=Nk △E _i .

These accumulated deviations are guided to the nonlinearization means 202, and the absolute value is a constant value a due to the characteristics shown in FIG.
The output E _i1 ′, E _i2 ′ for the integrated deviation above the dead zone of
is output.

The reason for providing the dead zone is to avoid changing the pressure if there is a minute cumulative deviation, since generally changing the shower pressure will cause a large disturbance to the profile.

203 is a shower pressure setting value calculation means;
Input the outputs E _i1 ′ and E _i2 ′ of the nonlinearization means and execute the following calculation to determine the pressure set values SV _1o and SV _2o for the next control cycle for the current pressure set values SV ₁ and SV ₂ . Calculate and feed to pressure regulator.

SV _1o = SV ₁ +b·E _i1 ' SV _2o = SV ₂ +b·E _i2 ' Here, b is a constant that can be established arbitrarily.

Note that when the pressure set value is changed, it takes time for the profile disturbance caused by this change to settle down, so a timer means (not shown) is used to hold the set value while the set value is not changed during this time. ) is executed.

FIG. 5 is a flowchart showing the signal processing procedure of each element of the control device described above.

<Effects of the Invention> As explained above, according to the present invention, the controllability of the profile at both ends of the slice lip is greatly improved, and the quality of the product is improved. Furthermore, since the amount of cut at the edge can be reduced, the effective area of the product can be made larger than before.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing the structure of the control device, Figs. 3 and 4 are explanatory diagrams of the operation of the control device, and Fig. 5 is a signal diagram of the control device. Flowchart showing processing steps, No. 6
The figure is a general configuration diagram of a paper machine, and FIG. 7 is a characteristic diagram showing an example of the result of profile control according to the prior art. 5... Head box, 6... Slice lip, 7... Slice bolt, 8... Wire part, 14, 15... Shower shower supply means, 16... Shower water supply pipe, 17... Pressure sensor, 18... Control valve, 19... Pressure regulator, 20... Control device.

Claims (1)

[Claims] 1 The operation output obtained by controlling and calculating the deviation between the basis weight profile measurement signal and the basis weight profile setting signal corresponding to each measurement point is transmitted to the slice bolt as the operation end corresponding to each measurement point, and the nodes provided at both ends of the head box are In a basis weight profile control device having pressure adjustment means for a deck shower, there is provided a means for calculating the integrated value of the deviations at a plurality of measurement points near both ends of the slice lip, and adjusting the pressure when the calculated output exceeds a dead zone. A basis weight profile control device comprising means for changing a set value of the means.